In a rotary anode X-ray tube, a disc portion is fitted into a rotary anode with a first gap therebetween and a fixed shaft is fitted into a rotary shaft to support the anode with a second gap therebetween. The disc portion and the fixed shaft are formed integral with each other to have a hollow portion therein. A cooling liquid is allowed to flow through the hollow portion. A liquid metal is filled in the first and second gaps. Dynamic pressure type bearings is formed in the second gap. A passage is formed to directly communicate the first gap to the second gap, whereby the liquid metal being directly supplied from the second gap to the first gap. Thus, the liquid metal can be fed rapidly and surely into the gap between the anode target and a cooling vessel.